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Gas Caps

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56pan
Posts: 33
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Bikes: 1956 FLH
1997 FLHTCI
Location: Eighty Four, PA

Gas Caps

#1

Post by 56pan » Sat Jul 19, 2008 1:41 am

I have a 1956 Pan that I just bought 2 new gas caps for. 1 vented and 1 non vented. Problem is the non vented one doesn't fit. It's longer underneath so when I put it on it just spins. The tabs are too far into the tank to catch. So, my question is do I need to use both vented caps? Won't that allow gas to leak out onto my tank when bike is on the jiffy stand? Any suggestions for a good cap. I bought the scalloped ones because they are easier to remove with my arthitus in my hands. Would like to have something like that. Thanks.
Bill



john HD
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#2

Post by john HD » Sat Jul 19, 2008 2:08 am

yes you need 2 vented caps.

mine do not leak when on the jiffy stand.

john

VT

#3

Post by VT » Sat Jul 19, 2008 2:16 am

Call Kick-Start (616) 245-899 M-F (EST). See what they have that's current for gas caps. At least they know what's good. 61103-36 is the only part number for pre-'65 caps. Vented ones.
The left cap was non-vented for 1965-up.

51Hog
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#4

Post by 51Hog » Sat Jul 19, 2008 5:43 am

john HD wrote:yes you need 2 vented caps.

mine do not leak when on the jiffy stand.

john
How do you keep it from leaking John?
Only way I have found is not to fill it up all the way.
I usually fill it up all of the way while sitting on the bike---Not on the jiffy.
If I put it on the jiffy before I burn 3/4 gallon, it will leak.
I need to put it on the rear stand if I show less than 25 miles on the trip odometer. 1951
I have often thought about putting a cross over vent between the tanks so I could put a non vented cap on the left tank and not have to worry about leaking fuel. I sometimes forget to put it on the rear stand when full. My paint is cooked below the filler cap, and the rubber on the footboard has also been damaged from the fuel dripping on it.

john HD
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#5

Post by john HD » Sat Jul 19, 2008 2:04 pm

how do i keep them from leaking?

on the stand i fill the left tank first, leave an inch of space then fill the right to the same level.

seems to work, you just cannot over fill them. i did find that a new old stock jiffy stand helps greatly. it seems my old one had gotten bent over the years.

john

51Hog
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#6

Post by 51Hog » Sat Jul 19, 2008 5:22 pm

I think that my stand must be bent. If I fill on the jiffy stand, and only to the level that does not leak, I can only put 2.5 gallons in my 3.5 gallon tanks. I wonder if I could get you to take a pic of your bike on the jiffy stand from the rear and post it here. I will measure the angle with a protractor and compare it to mine.
Thanks,
Dale

sprucecreek
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#7

Post by sprucecreek » Sat Jul 19, 2008 7:32 pm

I have found that the rubber gaskets on some of the replacement caps are not thick enough, and the fuel will slosh around when you ride and leak out the bottom of the caps. I ended up putting a thicker rubber on them, and now they seal ok.

56pan
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1997 FLHTCI
Location: Eighty Four, PA

#8

Post by 56pan » Sat Jul 19, 2008 7:40 pm

Thanks guys. I thought I needed 2 vented caps but now I am sure. This forum has been a great help to me and my PAN. Thanks again.
Bill

john HD
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#9

Post by john HD » Mon Jul 21, 2008 4:33 am

I think that my stand must be bent. If I fill on the jiffy stand, and only to the level that does not leak, I can only put 2.5 gallons in my 3.5 gallon tanks. I wonder if I could get you to take a pic of your bike on the jiffy stand from the rear and post it here. I will measure the angle with a protractor and compare it to mine.
Thanks,
here is a shot with a couple of other guys bikes, i would say mine is standing up about the same or a little higher than the rest.

john[/code]
You do not have the required permissions to view the files attached to this post.

51Hog
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#10

Post by 51Hog » Mon Jul 21, 2008 5:34 am

Thanks John. Just what I was looking for.
Mine leans as much or more than the bike to the left of yours.
Now I'll be looking to stand it up some.
Dale

awander
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#11

Post by awander » Fri Jul 25, 2008 1:27 am

Before I knew about this site, and I was doing things "my own way", I decided that the left gas cap on my '52 should be non-vented. I made sure that it was clean and dry(no gas in it) and soldered the vent holes on the bottom shut.

I have been using it that way for about a year, and it does help with the leaking problem. I never thought about it before, but since there is no vent line between the tanks, I wonder why I don't have any problems?

Maybe the gasket and cap are just leaky enough to let air in?

It does not seal completely, if I overfill it a lot, and put it on the side-stand, it will leak a little bit.

Paughco
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Re: Gas Caps

#12

Post by Paughco » Sun Jul 27, 2008 7:02 pm

Hi guys:

This is an interesting topic. I have had my '50 Pan since 1962. It was totally stock then, a baby blue FL. I never remember having a problem with gas leaking back then, except from the COPPER fuel line I had installed between the tank and the Linkert carb. I was 16 back then, and I didn't know about work hardening and all that other technical stuff. I am a licensed mechanical engineer today, and I attribute taking on that career to early experiences with my old Pan!

Things have changed from the old days, when you could ride up into Dudley Perkins (I think the shop was on Ellis Street back then) and order parts right off the shelf. The machine has also gone through plenty of changes over the years. Now she looks like a '60's Frisco Angels chopper, only with drag bars instead of apes, and a '77 Wideglide with a PM caliper.

One thing I found was that you have to "adjust" the fitment of those Taiwanese gas caps with a "Harley Davidson Tool Number One" (big 'ol hammer). You gently pound the raised center on the inside of the cap until the tabs lock on the stops in the tank and there is enough tension to allow the rubber seal to do its thing. I didn't make this up - I got it straight from Casey Wing, Chopper Guru of the Seattle area.

I've been running vented on the right side, and non-vented on the left, and I have to get going right after gassing up, and run at least half a gallon or so before parking on the side stand.

OK - enough rambling. Gotta go wash the bugs off my K1200S.

Seeya
ATB

VT

Re: Gas Caps

#13

Post by VT » Sun Jul 27, 2008 7:56 pm

My routine for filling the stock 3.5 gallon tanks on my Pan, is to fill the right tank first, to the top, then start filling the left tank to about 2" below the neck (my left tank has a non-vented cap, my right tank has a vented cap). Then I put both gas caps back on and the pump nozzle back into it's holder - snatch my pump receipt from the ticker-tape machine and start the motorcycle (the right tank is still gravity feeding the left tank, but it's not up to the left tank brim yet - now about 1" from overfilling).
To keep the left tank from spilling over, I make sure I ride the beast for at least 10 miles, so when I do stop, the fuel won't overflow the left tank. After 10 miles, the fuel volume has been reduced enough in both tanks, that on the jiffy stand, the right tank will only gravity feed fuel over to the left tank, until the left tank builds up enough head pressure that the remaining fuel in the right tank can't push against the left tank's mass anymore.
Having the correct kick-stand for reduced lean-over helps, and putting the machine on a Bestway or parallelogram lift keeps everything level until I ride it again. It's easier for me to check the fluid levels with the BT sitting level before a ride. And I check all the levels everytime I ride, except the 6V battery and that's once a month. Panheads are great motorcycles. Predictable and dependable.
I think the question of whether having a non-vented (left) tank cap and a (right) vented cap, and causing the left tank to fuel lock, is not a problem. If the right tank has a vented cap and the left tank doesn't, the right tank will "vent" the left tank too (aided by the fact that even with the rubber seal, the shut-off rod is not an air-tight seal when it's raised by the spring under the cap).
I thought having a non-vented (left) cap would reduce the spill-over but it doesn't and it's a fact that all pre-65 Big Twin caps were vented. I use V-Twins leather gas cap seals, but now I don't see them in the '08 catalog..
Note: That same "one vent for two need-to-be-vented appurtenances" situation applies to both intake lower spring covers on the Knuckle motor. You can have a vent hole in each spring cover, or you could have only one in the more (leeward) protected front cylinder lower cover. The motor would still vent the top end of a Knuckle until the single vent hole became clogged with dirt.
Although, some knuckles run fine without either of the lower covers having a vent hole.

51Hog
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Re: Gas Caps

#14

Post by 51Hog » Sun Jul 27, 2008 10:54 pm

I think the question of whether having a non-vented (left) tank cap and a (right) vented cap, and causing the left tank to fuel lock, is not a problem. If the right tank has a vented cap and the left tank doesn't, the right tank will "vent" the left tank too (aided by the fact that even with the rubber seal, the shut-off rod is not an air-tight seal when it's raised by the spring under the cap).
Actually, on my 51, I tried the non vented cap on the left. It does not work--at least not on my machine--my shut off rod does not leak air. My tanks vacuum locked.--The cure----Crack the cap to let air in and go back to the vented cap, or put in a cross over tube between the tops of the tanks.
Dale

VT

Re: Gas Caps

#15

Post by VT » Sun Jul 27, 2008 11:45 pm

The my non-vented cap must leak.
As a experiment: If you took two plastic milk jugs with screw tops; and glued a crossover line connecting the bottom of each milk jug, with the right jug fitted with a tee (bottom run of the tee would supply the carb and we've attached it to a carb that's pulling Linkert amounts of fuel).....then we leave the left jug's top screwed down tight and ran the motor. The motor will soon starve for gas, because we have both caps on tight.
Then we crack the cap on top of the right milk bottle.
1. Will gas flow to the carburetor?
2. Will it be left tank gas or right tank gas that feeds the carb? Or will the right tank gas mix with whatever left tank gas it wants, and the contents of both milk bottles feed the carb until they both run dry?
3. If venting the left tank only (and it would need to be a vent orifice equal to or greater than the drain demand orifice [carb]), would we ever need to release vacuum from the right tank?
I think the answer is yes. We would have to open the cap on the right tank, because the right tank needs to vent from the top. Hence the top crossover vent line on '65 and later tanks and the left tank's non-vented cap they used from 1965-up.

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